The present invention relates to an optical disk apparatus for an optical disk enclosed in a disk cartridge which is to be detachably inserted thereinto. More particularly, the invention relates to a dustproof structure for protecting an optical system of a optical pickup device disposed in a casing from dust contained in the atmosphere.
Generally, an optical disk apparatus for recording data on an optical disk and/or reproducing data from the same is equipped with various drive sources such as, for example, a disk drive motor for rotating the optical disk, a linear motor for moving an optical pickup device in the radial direction of the optical disk, as well as a semiconductor laser which is used as a light source of the optical pickup device and drive circuit elements for driving the drive sources and the light source. The heat generated from the drive and light sources and the drive circuit elements therefor, can raise the inside temperature of a standard type of optical disk apparatus by several tens of centigrade degrees.
Such a temperature, an optical disk or a semiconductor laser and shorten the service life thereof. Accordingly, it has been common to cool an apparatus such as drive unit using an optical disk apparatus with an air-intake fan.
On the other hand, generally, the optical disk apparatus for use with an optical disk enclosed in a insertable disk cartridge comprises a casing for accommodating the cartridge through a cartridge insertion aperture. A disk drive motor for rotating the optical disk, a loading assembly for detachably loading the cartridge on a disk drive motor, and an optical pickup device having an optical system such as objective lens for focusing a light beam on the optical disk are disposed in the casing. A slight gap is ensured between the optical disk and the objective lens of the optical pickup device so that the cartridge can be exchanged to another one.
In order to perform forced air-cooling in the casing, an air-inlet and air-outlet, each covered with a dust filter, are formed in the casing at its front and rear panel sections, respectively. Much of the of dust can be caught with the filter at the air-inlet.
Further, when the cartridge is pulled out from the casing through the cassette insertion aperture which is generally formed in the front panel of the casing, the cassette insertion aperture can be closed with the door member which is, in general, pivotally provided at the inside of the front panel section of the casing. However, when the cartridge is inserted into the casing through the cassette insertion aperture and is then loaded on the disk drive motor, the door member is maintained in its aperture-opening position by means of the cartridge. Accordingly, dust may be introduced into the case particularly through the cassette insertion aperture.
In such a construction of the optical pickup device, when forced air-cooling is performed in the casing, dust introduced into the casing ma flow through gaps between constituent parts within the casing, particularly through gaps between the constituent parts of the loading assembly and a gap between the cartridge and the loading assembly and, then, arrive at optical parts such as the objective lens, resulting in the contamination or pollution of the optical parts by adhesion of dust thereon.
As a result, an optical wave surface in the optical system is distorted, and thus the focusing efficiency or the data detection characteristics of the optical pickup device could suffer. Therefore, the reliability of the optical disk apparatus could be decreased due to frequent occurrence of data errors.